1. Field of the Invention
The invention generally relates to a circuit board, and more particularly, to a process of electronic structure.
2. Description of Related Art
The process of a circuit board can be roughly divided into laminating method and building-up method. The fabrication principle of the laminating method is to form a patterned metal circuit layer on a single surface or both surfaces of a dielectric layer. Then, a bonding sheet and a metal sheet are added on the circuit layers and meanwhile the metal sheet and the bonding sheet are heated and pressed so that the metal sheet is bonded with an adjacent circuit layer. After that, conductive through vias are fabricated on the laminated layers so that each of the circuit layers and the metal sheet can be electrically connected to each other through the conductive through via. On the other hand, the fabrication principle of the building-up method is to sequentially form a circuit layer, a dielectric layer and a metal layer respectively on both opposite surfaces of a carrier board, and the adjacent circuit layer and metal layer are electrically connected to each other through conductive blind vias formed in the process.